Electric control mechanism



Jan. 31, 1950 J. B. WHITTED ELECTRIC CONTROL MECHANISM s Sheets-Sheet 1 Filed Aug. 20, 1 943 54w, Mb? V 7E 22 65:."

Jan. 31, 1950 J. B. WHITTED 2,496,187

ELECTRIC CONTROL MECHANISM Filed Aug. 20, 1943 5 Sheets-Sheet 2 :i 'Tf.

- 30 l I J6 52 Jan. 31, 1950 Filed Aug. 20, 1943 J B. WHITTED ELECTRIC CONTROL MECHANISM 5 Sheets-Sheet 3 bar/alum:

/oz/ I i Jan. 31, 1950 J. B. WHlTTED 2,496,187

ELECTRIC CONTROL MECHANISM Filed Aug. 20, 1943 5 Sheets-Sheet 4 Q @l WW I 65 ,/08 v m8 Jan. 31, 1950 J. BLWHITTED 2,496,187

ELECTRIC comm. unacmmrsu Filed'Aug. 20, 1943 5 Sheets-Sheet 5 Patented Jan. 31, 1950 UNITED STATES PATENT 1 OFFICE.

John mm to Stewart-Warner Corporation,

corporation of Virginia Application August 20, 1943, Serial No. 499,338

16 Claims. (01. 137-139) 1 My invention relates to electric control mechanism, and is illustrated and described herein as being applied to a particular valve for controlling the iiow of ventilating airto the cabin of an aircraft. My invention, however, is not limited to such use and may be utilized generally as awhich may be inexpensively manufactured by conventional methods and with conventional machinery and equipment.

Another object of my invention is to provide new and improved electric control mechanism which is compact, light weight, and may be easily applied to existing machinery or equip-' ment. Other objects and advantages will become apparent as the description proceeds.

In the drawings,

Fig. 1 is an elevational view partly in section showing a preferred form of my invention applied to a valve;

Fig. 2 is a top plan view of the mechanism Fig. 1; 7 1 a sectional view taken on the line partial, sectional view taken genline 4-4 of Fig. 3, but with parts roken away to show the structure therebeneath;

a partial, sectional view taken on the 6-5 of Fig. 3,

is a pa ial, irregular section taken on 1--'| of Fig. 3:

Fig. is a partial, sectional view taken on the line 3-8 of Fig. "I; and r Fig. 9 is a wiring diagram.

In the drawings, I have illustrated my electric control mechanism asbeing applied to a valve which is schematically shown as having a body it rotatably-supporting a shaft i2 carrying a movsectional view taken on the line 8-6 worm 32, which in turn rotates a worm wheel 34 s Chicago, lit, I

positions to regulate flow of ventilating air or other fluid through the valve body and ducts connected therewith. This valve may be the fourway valve disclosed and claimed in my copending application, Serial No. 496,353, filed July 2 1943, now Patent No. 2,388,890 of November 13, 1945, and is herein referred to as controlling the now of ventilating air to the cabin or other enclosed space of an aircraft.

In aircraft practice it is common to heat the ventilating air by means of an internal combustion type of heater, and under certain circumstances this heater may discharge carbon monoxide or other toxic gases into the ventilating air. My novel control is herein described as reacting to the presence of such toxic gases automatically to shift the movable vane to position to prevent such gases from entering the aircraft cabin. While such an application of my invention is one for which my invention is particularly adapted, it is to be understood that this application is selected for purposes of illustration only and that my electric control mechanism is equally applicable to control other types of valves used for suitable manner. The base 20 is attached to supporting bosses 24 by screws 25 (Fig. 6), or in any other convenient manner. The bosses 24 may be integral with the valve body II, but in the particular embodiment shown are illustrated as being integral parts of a plate It brazed or otherwise secured to this valve body.

A reversible electric motor, indicated generally by reference character 23, is mounted on the housing It and has a casing which issecured to the cover it by screws III. This motor drives a mounted on a shaft "L iournaled inbearings ll and 40. The bearing" comprises a bushing ll press fitted directly into a bore formed in the housing i6, whereas the bearing 40 comprises a bushing 44 supported in a plate 48 attachedto its upper end Journaled in a bushing ll, mounted in the cover I I.

- The lower end of this shaft is Journaled in a driving sleeve 53 which passes through an opening able vane i4 adapted to be shifted to different 55 in the base fl and projects into the end ofthe valve shaft II. A pin I carried by the operating shaft 5. lies in suitable notches formed in the upper end of the valve shaft and forms a driving connection between these shafts. This pin is also adapted to engage an eccentric stop I! which may be pre-set so that the vane II is in closed position when the pin Cl engages this stop. In other words, the position of this stop corresponds to the zero position of the valve vane referred to in my said copending application.

A gear 84 is fixed to the vertical shaft I4 and drives a gear 8! mounted in a yoke 66 having a stem '8 slidably-mounted in a fixed pole piece ll of a solenoid I2. A pin II carried by one end of the solenoid and projecting into a suitable bore in the yoke prevents rotation of this yoke about the axis of the stem ll. Armature H is clamped between a shoulder of the stem '8 and a cap it threadedly secured to the righthand end of this stem. A leaf spring II is confined between the cap I. and the adjacent end of the solenoid I2 and holds the parts in the position shown in Pig. 3, except when the solenoid I2 is energized.

The tubular operating shaft 58 has a gear 8| affixed to its upper end for driving this shaft. This gear ill is of slightly smaller diameter than the gear, as clearly shown in Fig. 3. When the gear 55 and yoke 66 are in the position shown in this figure, gear 85 meshes with and is driven by gear 64 but does not engage the teeth of gear 80. When, however, the solenoid I2 is energized, armature H is drawn into engagement with pole piece 10, and yoke 66 and gear 65 are moved to the left sufficiently to engage the teeth of gears 65 and 8D, whereupongear 55 forms a driving connection between gears it and 80.

An arcuate support 82 of L-shaped cross-section is secured to the base by screws I4 which pass through slots 86, whereby this support may be adjusted about the axis of the shaft 58. This support carries an arcuate electrical resistance 90 which is insulated from the support in any suitable manner. This resistance is engaged by a slider 92 carried by a pin 94 mounted in and electrically grounded through the operat ng shaft 58. One end of the resistance is connected to an electrical terminal 96.

An arcuate strip 98 of insulating material is attached to the base III by screws I" and carries a pair of limit switches indicated generally by reference characters A and B. Each limit' switch comprises a metal switch member III having a rigid upstanding arm I carrying a fixed contact and a second switch member ill having a resilient upstanding arm Ill carrying a movable contact which is normally in engagement with the fixed contact. The resilient arms project upwardly above the rigid arms and are adapted to be engaged by a bar Ill attached to gear 80. In the embodiment shown, the gear ll is of nonconducting material so that no insulation is needed between the switch operating bar iii! and this gear, but where the sear is made of metal, insulation must be provided so that the bar III is not grounded through the gear.

In Fig. 9 I have indicated a preferred arrangement of electrical connections for my novel con- 4 ismounied onthe instrument panel of the aircraft. A wire in connects the terminal III with the terminal I24 of an indicator Ill having a pointer, which may 'move over any suitable scale and which assumes a position accurately indicating and corresponding to the position of the vane H or other movable element operated by my control mechanism.

The other terminal I II of the indicator in is connected by wire III to the terminal III of a terminal fitting I" attached to the housing ll. An electrical conductor I30 connects the terminal it! with one end of the resistance II, the other end of this resistance .being grounded as indicated at III. The slider 92 variably engages the resistance to short out more or less of this resistance and thereby vary the position of the indicator pointer to correspond to the position of the valve vane since the slider I: is attached to and moves with the vane operating shaft N.-

In the particular embodiment shown I have provided emergency means for moving the valve vane to fully closed position if any carbon monoxide is present in the ventilating air supplied to the aircraft cabin. This means comprises a carbon monoxide detector ill of the comparator type having a fresh air inlet pipe I and a fresh air outlet pipe I. This detector also has a ventilating air inlet pipe I and a ventilating air outlet pipe I48, and operates by comparing samples of fresh or atmospheric air with samples of ventilating air. If carbon monoxide is present in the ventilating air, the detector ill functions to open a normally closed switch Ill located in a circuit comprising wires I52, I84, I56, I58, lit, and I62 serving normally to maintain the battery H2 connected to the solenoid coil 12.

In normal operation the closed switch I" and circuit of which it forms a part supplies current to solenoid coil 12 causing this coil to hold the gear 65 in outward position where it engages cooperating gears 64 and III to form a driving connection therebetween. Presence of carbon monoxide in the ventilating air causes the detector I40 to open switch I50 and break this circuit. Spring II thereupon retracts gear II to the position shown in Fig. 3, and thereby disconnects gear" from gear 64. A spiral spring I64 (Fig. 3) having one end attached to operating shaft 58 and the other end attached to housing Ii, thereupon rotates this operating shaft to move the valve vane It to fully closed position.

Further movement of the valve vane under the influence of spring I is arrested by engagement of pin ill with stop 62. In some applications engagement of the movable element of the valve or other mechanism with an associated stationary part will of itself constitute a sumcient stop and eccentric stop 82 may be eliminated. In other instances the stop 62 may be essential, whereas in a third class of applications the presence of stop I: may not be necessary but may be advisable as an additional protection.

It is only under very exceptional circumstances that carbon monoxide is present in the ventilating air supplied to the aircraft cabin, so that under normal operating conditions the solenoid 12 will hold gear 65 in power transmitting position and the valve vane may be shifted to any desired position by driving the motor 28 in the desired direction and to the desired extent. This is accomplished by pressing on one or the other tothebatterybywires ltlandlf'throughmaster switch I. The lower or movable contact of switch C'is connected by wiresi'll, "Land I'll to one terminal of limit switch 3.

The other terminal of this limit switch is connected by a wire In to the rlghthand halfof motor field coil Ill and through motor armature ill to ground. When the pilot holds hi finger on switch C, current is supplied to the motor II to drive it in one direction unleu the limit switch 3 is open; that is, unless the valve is already at the extreme limit of its movement in this direction. If thelimit switch is not in such extreme position, the motor drives valve shaft i! to move the valve vane in the desired direction, and as this movement takes place, slider 02 is moved over resistance 0! to cause the pointer of indicator I26 to follow the movement of the valve vane. when this pointer shows that the valve vane has reached the desired position the pilot releases his finger from the switch C.

when the pilot desires to shift'the valve vane in the opposite direction, he presses on the lower or movable contact of switch D to close this switch and deliver current through wires I82, I, and I86, limit switch A, and wire Ill to the ,lefthand half of motor field coil Ill and through motor armature I". This causes the motor 28 to drive the valve vane and resistance slider in the opposite direction, and may be continued until limit switch A is opened by bar ill. The limit switches Aand B are so positioned that the appropriate switch is opened just before the valve vane reaches the extreme limit of its movement.

As previously pointed out, the solenoid II is normally energized to hold the gear 85 in driving relation with gears 64 and II. When this solenoid is no longer energized and spring ll moves gear" to the position shown in Fig. 3, this gear is still in mesh with gear 84. This means that as soon as the solenoid is again energized and motor 28 is driven in either direction, gear I! is' rotated so that it will easily slide into engagement with gear and no situation can. arise where the teeth of gears 68 and It would contact in such manner as to prevent outward movement of gear 85 into full mesh with gear ll. When gear 65. is in driving engagement with gears 64 and 80, worm 50 and worm wheel 52 prevent tion of said solenoid and thereby the connection of the motor to the shaft.

2. Electric control mechanism of the class described, comprising a two-part housing. a motor carried by said housing, a worm driven by said ond worm wheel, a gear mounted on said second shaft, a third shaft in alignment with said second shaft, a second gear mounted on said second shaft, one of said gears being of slightly smaller diameter than the other, a third gear adapted tomesh with said other gears and form a driving connection between said second and third shafts, said third gear being shiftable to engage one or both of said other gears, a solenoid for moving said third gear in one direction, and emergency control mechanism for deenergizing said-solenoid;

3. Electric control mechanism of the class described, comprising a two-part housing, a motor carried by said housing, a worm driven by said motor, a first shaft in said housing, a first worm wheel mounted on said first shaft, a second shaft mounted in said housing, a second worm wheel mounted on said second shaft, a second worm mounted on said first shaft for driving said second worm wheel, a gear mounted on said second shaft, a third shaft in alignment with said second shaft, asecond gear mounted on said second shaft, one of said gears being of slightly smaller diameter than the other, a third gear adapted to mesh with said other gears and form a driving connection between said second and third shafts, said third gear being shiftable to engage One or both of said other gears, a solenoid for moving said third gear in one direction, a spring for moving said third gear in opposition to said solenoid, and a secondljspring for rotating said third shaft in'one direction when said third gear is disconspring I 64 from moving the valve vane to closed position when the motor 20 is at rest.

While I have shown and described in detail only a single embodiment of my invention, it is to be understood that my invention is susceptible of numerous variations and modifications and includes all modifications, variations and equiva-. 1

nected from one of said other gears.

4. Electric control mechanism of the class described, comprising an operating shaft, a housing rotatably supporting said shaft, 9, motor carried by ,said housing, driving means connecting said motor and shaft, said driving means including a clutch, a solenoid controlling said clutch, a spring for driving said shaft when said clutch is disengaged, and switch means for operating said solenoid.

5. Electric control mechanism of the class -described, comprising a housing, a first shaft having one end iournaled'in said housing, a motor for driving said shaft, a tubular-second shaft having one end joumaled in said housing, said first and second shafts being telescoped, a clutch connecting said shafts, electrical means controlling said clutch, a spiral'spring surrounding said second shaft and having one end connected thereto, said spring having a second end connected to said housing and urging said second shaft in a given direction, and van eccentric stop adjustable to limit movement of said second shaft under the force of said spring.

described, comprising an operating shaft adapted tobe attached to the movable element of a valve,

a motor for driving said shaft, a means including switch means for supplying current to said motor selectively to operate it in opposite directions, a clutch between said motor and shaft, a solenoid for holding said clutch in engagement, and a carbon monoxide detector controlling energizalimit switches for limiting movement of said operating shaft in opposite directions, a spring for moving said shaft in one direction, means for limiting movement of said shaft by said spring, and means movable with said operating shaft for actuating said limit switches.

'1. Electrical control mechanism of the class described, comprising an operating shaft adapted to be attached to the movable element of a mechanism to be controlled, a motor for driving said shaft, means including manually operable switch means for supplying current tosaid motor, a clutch between said motor and shaft, means normally tending to disengase said clutch, a solenoid for holding said clutch in engagement, and a toxic gas detector controlling energization of said solenoid.

8. Electric control mechanism of the class described, comprising a housing, a motor carried by said housing, a first shaft driven by said motor, a gear mounted on said first shaft, a second shaft in alignment with said first shaft, a second gear mounted on said second shaft, one of said gears being of slightly smaller diameter than the other,

a third gear adapted to mesh with said other gears and form a driving connection between said second and third shafts, said third gear being shiftable to engage one or both of said other gears, a solenoid for moving said third gear in one di-- rection, and emergency control mechanism for deenergizing said solenoid.

9. Electric control mechanism of the class described, comprising a two-part housing, a motor carried by said housing, a worm driven by said motor, a first shaft in said housing, a first worm wheel mounted on said first shaft, a second shaft mounted in said housing, a second worm wheel mounted on said second shaft, a second worm mounted on said first shaft for driving said second worm wheel, a gear mounted on said second shaft, a third shaft in alignment with said second shaft, a second gear mounted on said second shaft, one of said gears being of slightly smaller diameter than the other, a third gear adapted to mesh with said other gears and form a driving connection between said second and third shafts, said third gear being shiftable to engage one or both of said other gears, electrical means for moving said third gear in one direction, a spring for moving said third gear in opposition to said solenoid, a second spring for rotating said third shaft in one direction when said third gear is disconnccted from one of said other 'gears, and an emergency switch controlling said electrical means.

10. Electric control mechanism of the class described, comprising an operating shaft, a housing rotatably supporting said shaft, a motor carried by said housing, driving means connect ng said motor and shaft, said driving means including a clutch, a solenoid controlling said clutch, a spring for driving said shaft when said clutch is disengaged, switch means for operating said solenoid, and indicating means responsive to movements of said shaft.

11. Electric control mechanism. of the c ass described, comprisrig a housing, a first shaft having one end journaled in said housing, a motor for driving said shaft, a tubular second shaft having one end journaled in said housing, said first and second shafts being telescoped, a clutch connecting said shafts, electrical means controlling said clutch, a spiral spring surrounding said second shaft and having one end connected thereto, said spring having a second end connected to said housing and urging said second shaft in a given direction. a stop adjustable to limit movement of said second shaft under the force of said spring, and an indicator having a rheostet driven by said second shaft. T

12. Electric control mechanism of the clam described, comprising an operating shaft, a motor for driving said shaft in opposite directions, a pair of manual switches controlling emergintion of said motor, an indicator for indicating the position of said operating shaft, a rheostat connected to said operating shaft and said indicator, .Jlimit switches for limiting movement of said operating shaft in opposite directions, means movable with said operating shaft for actuating said limit switches, and an automatic switch operable to return said shaft to one limit of its movement.

13. Electrical control mechanism of the class described comprising a ventilating air valve having operating mechanism including a movable element, an operating shaft attached to the movable element of the valve, said element assuming different positions corresponding to different positions of said shaft, a reversible motor for driving said shaft, means including a pair of manual switches for operating said motor in different directions, electrical circuits connecting said switches with said motor, a clutch connecting said motor with said operating shaft, a solenoid for holding said clutch in engagement, spring means for moving said clutch out of engagement, said movable element being biased to closed position when said clutch is disengaged, an indicator for showing the position of said valve element, means connecting said indicator to said shaft, and means responsive to the presence of carbon monoxide in the ventilating air for deenergizing said solenoid.

14, Electrical control mechanism of the class described comprising a ventilating air valve having operating mechanism including a movable element, an operating shaft attached to'the element, said element assuming different positions corresponding to different positions of said operating shaft, a reversible motor for driving said shaft in opposite directions, means connected to said motor and including manual means controlling the direction of rotation of said motor for operating the motor in opposite directions, an indicator for indicating the position of said valve element, means connecting said indicator to said shaft, a clutch connecting said motor and shaft, a solenoid for holding said clutch engaged,

means responsive to the presence of carbon monoxide in the ventilating aid for deenergizing said solenoid, a spring for moving said shaft to close said valve when said solenoid is deenergized, and an adjustable stop for limiting movement of said operating shaft under the influence of said spring.

15. Electrical control mechanism of theciass described comprising a ventilating air valve having operating mechanism including a movable element, an operating shaft attached to said element, the movable element of the ventilating air valve assuming like positions with said shaft, a reversible motor for driving said shaft, means connected to said motor and including manually operated switch means for driving said motor in different directions, a clutch connecting said motor with said operating shaft, electrical means for holding said clutch in engagement, spring means for moving said clutch out of engagement,

and means responsive to the presence of. toxic gas in the ventilating air for deenergizing said electrical means:

16. Electrical control mechanism of the class described comprising a ventilating air valve having operating mechanism including a movable element, an operating shaft attached to the movable element of the valve, said movable element assuming positions corresponding to the positions assumed by said shaft, a reversible motor for driving said shaft in opposite directions, means connected to said motor and including manual means controlling the direction of rotation of said motor for operating the motor in opposite directions, an indicator for indicating the position of said valve member, means connecting said indicator to said shaft, a clutch connecting said motor and shaft, means for holding said clutch engaged, means responsive to the presence of an impurity in the ventilating air for rendering said last named means ineffective, a spring for moving said shaft to close said valve when said solenoid is deenergized, and a stop for limiting movement of said operating shaft under the influence of said spring.

JOHN B. WHII'IED.

- 1O nnmamcns mm The following references are of record in the file of this patent:

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